This invention relates to pneumatic spring assemblies, sometimes called gas cylinders or gas springs. Such gas cylinders are commonly employed to assist in movement of doors or lids on vehicles or machines and the like e.g., for trunk lids or hatchback lids on automobiles, and for retaining such in one position, usually the open position.
In several of the usages of such gas cylinders, the weight of the lid or door might overcome the bias of the gas cylinder and allow the lid or door to drop prematurely. Consequently, manufacturers of such cylinders have heretofore developed various types of latches to retain the gas cylinders in an extended or partly extended condition. Japanese patent application No. 14,636 and German patent document No. 3,442,262 disclose a cocking sleeve arrangement wherein the sleeve can be cocked or tilted from one position aligned with the cylinder to a second position axially at an angle to the cylinder so that an offset end ledge or surface of the sleeve will engage the end of the cylinder to prevent its retraction. Unfortunately, such an arrangement can be accidentally released as by being bumped, allowing the lid to fall. Two other arrangements which have been marketed by the assignee herein involve (A) the use of a laterally extending V-shaped spring arm or lever mounted on the piston rod and having an end biased to be cocked laterally to engage the end of the fluid cylinder, and (B) a leaf spring-biased plate which is slid between the end of a fully extended cylinder and the end of an elongated sleeve spaced from the cylinder. U.S. Pat. No. 4,078,779 employs a leaf spring along side the cylinder to enable a pin to retain the cylinder in a partially extended position against further extension of the cylinder. U.S. Pat. No. 3,789,742 employs a spring arm to retain the cylinder in a retracted position. U.S. Pat. No. 3,851,867 has a pivotal element with an arcuate cam slot interfitted with a follower pin to control the position of the pneumatic actuator. Japanese application No. 57-186,647 provides a rotatable interfit between a cylinder and a cover.